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S. L. Stevenson (SAO), J. Melbourne (UCSC)
The nature and formation history of luminous compact blue galaxies (LCBGs) is an open question. Of particular interest is the degree to which high energy phenomena such as AGN and X-ray luminous starbursts are associated with LCBGs. We seek to find a partial answer to the question of LCBG formation through an analysis of X-ray and optical data, representing a sample of X-ray detected LCBGs in the GOODS/CDF-N survey area.LCBGs selection is based on optical photometry of the ACS GOODS images and redshifts from the Team Keck Redshift Survey (TKRS). With absolute magnitude MB < -18.5, color (B-V) < 0.6 and surface brightness SBe < 21, we find 288 LCBGs in TKRS. Positional correlation with the CDF-N point source catalog is then performed, yielding a sample of 12 X-ray selected objects. A crude morphological examination reveals that 50% (6) of the objects have spiral structure, and 75% (9) have irregular morphologies which appear to be due to tidal disturbances, possibly indicative of an interaction or merger. In 50 % of the sample, the X-ray source appears coincident with the optical center. However, for the remainder of the LCBGs, the X-ray source, while localized within the region of optical emission, is offset from the optical center, possibly indicating a non-nuclear starburst event. The fact that only ~5% of the TKRS LCBGs are detected at X-ray wavelengths at the low detection threshold of the CDF-N is interesting, and indicates that high-energy processes, such as AGN activity, are relatively rare in the population of LCBGs. When LCBGs are detected in the x-ray, they appear to be associated with interactions.
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Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.